Answer:
A. Opportunity cost.
Step-by-step explanation:
Opportunity cost shows a relationship between scarcity and choice. The choice and best source of sales for Maria's company is through online product request on e-store website.
The company has two options for sales, the online sales and physical sales in the company itself. When the company's system fails, they decide to focus on the physical sales for the duration of the system failure.
The opportunity cost is the online sales which was put aside for physical sales.